Unit 3 Stratosphere

Question 1

Stratosphere

Answer 1

The layer of the atmosphere above the troposphere. It extends from 10 km to about 50 km above Earth’s surface. The air in the stratosphere is very thin compared to the air in the troposphere. Some aeroplanes, like commercial jets, are able to fly in the stratosphere. They use less fuel flying here because they can pass through the air of lower density more easily than through air of higher density lower down. It is also safer to fly in the stratosphere as it is above the stormy weather of the troposphere.

Question 2

ozone

Answer 2

a form of oxygen found mainly in the stratosphere

Question 3

ozone layer

Answer 3

the band in the stratosphere in which most of the atmosphere’s ozone is found

Question 4

ultraviolet radiation

Answer 4

radiation from the Sun that has a shorter wavelength than the violet light in the visible light spectrum.

Question 5

Ozone in the stratosphere

Answer 5

The stratosphere includes a band of ozone gas known as the ozone layer. Ozone is a form of oxygen in which the molecules have three atoms (O3), instead of the usual two (O2). The ozone layer occurs at about 10-40 km above Earth’s surface - in the lowest part of the stratosphere.

Question 6

Ozone absorbs ultraviolet radiation

Answer 6

Ozone is a very important gas in the atmosphere because it absorbs ultraviolet radiation from the Sun. Ultraviolet radiation (also known as UV radiation) is radiation that has a shorter wavelength than the violet light of the visible light spectrum. As this shortwave radiation passes through the atmosphere toward Earth, a lot of it is absorbed by the ozone in the stratosphere.

Question 7

The absorption of ultraviolet radiation warms the stratosphere

Answer 7

The absorption of ultraviolet radiation increases the temperature of the stratosphere. As a result, the further away from Earth, the warmer the air becomes.

Question 8

The absorption of ultraviolet radiation protects life on Earth

Answer 8

Too much ultraviolet radiation interferes with life on Earth in several ways. It affects: • Human health: Exposure to short amounts of UV radiation can cause sunburn. Exposure to larger amounts over a longer time is more serious because it can: • cause skin cancer, which can spread and lead to death cause a clouding condition, called a cataract, to develop in the lens of the human eye, leading to loss of vision • suppress the human immune system, increasing the risk of illness. Photosynthesis: Photosynthesis is the process in which the Sun’s light energy is converted into sugars in plants. The light energy is absorbed by chlorophyll in the leaves. Ultraviolet radiation can damage the chlorophyll and hence the plant’s ability to produce sugars and grow. Life cycles and sizes of populations: UV radiation can damage fish, amphibian and other animals in their early stages of development, and can affect their ability to reproduce. This has an impact on the life cycle of these animals, and leads to a reduction in the size of their populations. By absorbing some of the ultraviolet radiation, ozone protects Earth from its harmful effects on life on Earth. Although the stratosphere is more than 10 km above Earth, human activities can affect it. You will find out how in the next activity.

Question 9

Protect yourself from UV radiation

Answer 9

by wearing a hat, sunscreen and sunglasses with a UV filter. Keep out of the Sun in the middle of the day, and never look directly at the Sun.